tim keller talks about two kinds of fear in this sermon based on psalm 3 - fear of an immediate threat, and persistent anxiety -

he says there are two different kind of fear...

fear (like a car heading toward you and you run out of the way): a healthy response to danger, which drives us to fight or flight, and then is gone.

anxiety (the feeling the rest of the day after the car almost hit you that you are fragile, that anything could happen at any moment): a lingering, generalised, undefined sense of fear which paralyses us.

if fear is a thunderstorm, anxiety is a constant, cold drizzle. the thunderstorm produces green growth and replenishes the earth, the second constant drizzle produces mildew. fear can be good for us - it forces us to react and can save our lives - but anxiety just makes us agitated, nervous and upset. and constant anxiety can permanently turn on our autonomic nervous system, which is meant to respond to crises events only, and so lead to all kinds of health issues.

and what causes this debilitating kind of anxiety driven constant fear is not a threat to life or safety, but a threat to our identity: when something that makes us feel in control is threatened or taken away...

i have never read george macdonald's fairy tale "the princess and the goblin" but i have to after hearing this sermon. dr. keller uses part of the story to remind us to "follow the thread of faith..."

in the story the princess' fairy grandmother gives her a magical thread and these instructions...

" 'If ever you find yourself in any danger – such, for example, as you were in this same evening – you must take off your ring and put it under the pillow of your bed. Then you must lay your finger, the same that wore the ring, upon the thread, and follow the thread wherever it leads you.’‘Oh, how delightful! It will lead me to you, grandmother, I know!’

‘Yes. But, remember, it may seem to you a very roundabout way indeed, and you must not doubt the thread. Of one thing you may be sure, that while you hold it, I hold it too.’"

however later when the princess uses the thread it doesn't take her directly back to her grandmother. it seems to take her deeper and deeper into danger. she becomes more and more afraid. dr. keller uses the story as an illustration of obedience especially in the face of fear. the princess realizes that the thread only goes forward. if she tries to go back the way she came, it disappears.

when God calls us to obey, there are only 2 possible responses: obedience, which is hard; and disobedience, which my seem easier in the moment but in the long run is even harder. obedience may seem to take us into danger, but backwards lies disaster. so we face our fear and go forward. knowing that we have a Commander-In-Chief who has already won the battle and who is our sword and shield in the midst of the battle.